tests/protocol/test-both-ends-cancel.sh: Delete this test

It tests a corner case that we don't experience in real life (although
it can happen).  Moreover the test often hangs, so we're not proving
anything except that there's a very obscure bug that we haven't fixed
and probably won't ever fix.

tests/Makefile.am

@@ -554,7 +554,6 @@ parallel_test_parallel_LDADD = \
 	$(top_builddir)/gnulib/lib/libgnu.la
 
 TESTS += \
-	protocol/test-both-ends-cancel.sh \
 	protocol/test-cancellation-download-librarycancels.sh \
 	protocol/test-cancellation-upload-daemoncancels.sh \
 	protocol/test-error-messages \
@@ -563,7 +562,6 @@ TESTS += \
 	protocol/test-qemudie-midcommand.sh \
 	protocol/test-qemudie-synch.sh
 EXTRA_DIST += \
-	protocol/test-both-ends-cancel.sh \
 	protocol/test-cancellation-download-librarycancels.sh \
 	protocol/test-cancellation-upload-daemoncancels.sh \
 	protocol/test-launch-race.pl \

tests/protocol/test-both-ends-cancel.sh

@@ -1,34 +0,0 @@
-#!/bin/bash -
-# libguestfs
-# Copyright (C) 2010-2025 Red Hat Inc.
-#
-# This program is free software; you can redistribute it and/or modify
-# it under the terms of the GNU General Public License as published by
-# the Free Software Foundation; either version 2 of the License, or
-# (at your option) any later version.
-#
-# This program is distributed in the hope that it will be useful,
-# but WITHOUT ANY WARRANTY; without even the implied warranty of
-# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-# GNU General Public License for more details.
-#
-# You should have received a copy of the GNU General Public License
-# along with this program; if not, write to the Free Software
-# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
-
-# Regression test for:
-# https://bugzilla.redhat.com/show_bug.cgi?id=576879#c5
-# where both ends send cancel messages simultaneously.
-
-source ./functions.sh
-set -e
-set -x
-
-skip_if_skipped
-
-guestfish <<EOF
-scratch 100M
-run
--tar-in /tmp/nosuchfile /blah
-ping-daemon
-EOF